<?php

/*
 * This file is part of SwiftMailer.
 * (c) 2004-2009 Chris Corbyn
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

/**
 * Handles RFC 2231 specified Encoding in Swift Mailer.
 *
 * @package    Swift
 * @subpackage Encoder
 * @author     Chris Corbyn
 */
class Swift_Encoder_Rfc2231Encoder implements Swift_Encoder
{
	/**
	 * A character stream to use when reading a string as characters instead of bytes.
	 *
	 * @var Swift_CharacterStream
	 */
	private $_charStream;

	/**
	 * Creates a new Rfc2231Encoder using the given character stream instance.
	 *
	 * @param Swift_CharacterStream
	 */
	public function __construct(Swift_CharacterStream $charStream)
	{
		$this->_charStream = $charStream;
	}

	/**
	 * Takes an unencoded string and produces a string encoded according to
	 * RFC 2231 from it.
	 *
	 * @param string $string
	 * @param integer $firstLineOffset
	 * @param integer $maxLineLength optional, 0 indicates the default of 75 bytes
	 *
	 * @return string
	 */
	public function encodeString($string, $firstLineOffset = 0, $maxLineLength = 0)
	{
		$lines = array();
		$lineCount = 0;
		$lines[] = '';
		$currentLine =& $lines[$lineCount++];

		if (0 >= $maxLineLength) {
			$maxLineLength = 75;
		}

		$this->_charStream->flushContents();
		$this->_charStream->importString($string);

		$thisLineLength = $maxLineLength - $firstLineOffset;

		while (false !== $char = $this->_charStream->read(4)) {
			$encodedChar = rawurlencode($char);
			if (0 != strlen($currentLine)
				&& strlen($currentLine . $encodedChar) > $thisLineLength
			) {
				$lines[] = '';
				$currentLine =& $lines[$lineCount++];
				$thisLineLength = $maxLineLength;
			}
			$currentLine .= $encodedChar;
		}

		return implode("\r\n", $lines);
	}

	/**
	 * Updates the charset used.
	 *
	 * @param string $charset
	 */
	public function charsetChanged($charset)
	{
		$this->_charStream->setCharacterSet($charset);
	}
}
